package org.layui.shop.controller;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * 实现验证码
 *
 * @author ZQX
 * @date 2024-12-03
 */
@WebServlet("/code.jpg")
public class CodeServlet extends BaseController {
    private static final long serialVersionUID = 1L;

    // 设置字母的大小,大小
    private Font mFont = new Font("Times New Roman", Font.PLAIN, 17);

    // 随机产生颜色
    Color getRandColor(int fc, int bc) {
        Random random = new Random();
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

    public void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //设置头信息:设置页面不缓存
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);

        // 表明生成的响应是图片
        response.setContentType("image/jpeg");

        //在内存中创建图象
        int width = 100, height = 18;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        // 获取图形上下文
        Graphics g = image.getGraphics();
        //实例化随机类对象
        Random random = new Random();

        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(1, 1, width - 1, height - 1);

        // 画边框
        g.setColor(new Color(102, 102, 102));
        g.drawRect(0, 0, width - 1, height - 1);

        // 设置字体、颜色
        g.setFont(mFont);
        g.setColor(getRandColor(160, 200));

        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        for (int i = 0; i < 155; i++) {
            int x = random.nextInt(width - 1);
            int y = random.nextInt(height - 1);
            int xl = random.nextInt(6) + 1;
            int yl = random.nextInt(12) + 1;
            g.drawLine(x, y, x + xl, y + yl);
        }

        // 从另一方向画随机线
        for (int i = 0; i < 70; i++) {
            int x = random.nextInt(width - 1);
            int y = random.nextInt(height - 1);
            int xl = random.nextInt(12) + 1;
            int yl = random.nextInt(6) + 1;
            g.drawLine(x, y, x - xl, y - yl);
        }

        // 生成随机数,并将随机数字转换为字母
        String sRand = "";
        for (int i = 0; i < 6; i++) {
            int itmp = random.nextInt(26) + 65;
            char ctmp = (char) itmp;
            sRand += String.valueOf(ctmp);
            g.setColor(new Color(20 + random.nextInt(110),
                    20 + random.nextInt(110), 20 + random.nextInt(110)));
            g.drawString(String.valueOf(ctmp), 15 * i + 10, 16);
        }

        //把随机产生的六位字符设置在会话中
        HttpSession session = request.getSession(true);
        session.setAttribute("rand", sRand);

        // 图象生效
        g.dispose();
        // 输出图象到页面
        ImageIO.write(image, "JPEG", response.getOutputStream());
    }
}
